This part is a kind of semiconductor called AAT4280-3.

Function of this product has Slew Rate Controlled Load Switch.

Manufacturers : Advanced Analogic Technologies

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Some of the text within the PDF file :

AAT4280 Slew Rate Controlled Load Switch General Description The AAT4280 SmartSwitch™ is a member of AATI's Application Specific Power MOSFET™ (ASPM™) product family. The AAT4280 is a P-channel MOSFET power switch designed for high-side loadswitching applications. The P-channel MOSFET device has a typical RDS(ON) of 80mΩ, allowing increased load switch power handling capacity. This device is available in three different versions with flexible turn on and off characteristics from very fast to slew rate limited. The standard AAT4280 (-1) version has a slew rate limited turn on load switch and is functionally compatible with the AAT4250 device while offering superior RDS(ON) characteristics. The AAT4280 (-2) version features fast load switch turn on capabilities, typically less than 2 [ ... ]

AAT4280-3 PDF Datasheet Download